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Old Aug 21, 2012, 11:28 PM
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Originally Posted by Edmond Hui View Post
I think it's paper. It's absolutely true- reduce the wing loading for a given reynolds number and you'll reduce the natural flying speed. When you go from trot-along glider to genuine walkalong glider, something magical happens. I think this is an important video for all schools. Why is something so obviously achievable, technologically both advanced and simple, full of handles into flight and evolution, not taught as a standard part of the curriculum? It should be one of those classes that you remember forever.

Thanks for sharing that. My Paperang Moth looks like a cargo ship by comparison. Does anyone know definitively what the material is?

By the way, the original blog that the video comes from is translated by google thus:
http://translate.google.com/translat...901%2Fpaperfly

Lots more interesting stuff there. It think it's definitely paper. And it's clearly a part of a fairly big project in Taiwan.
I believe the paperang design would work just as well with a lighter material. Walkalong gliding depends on properly trimming the glider as mentioned in Ed's TED talk. The lightest paper I have used is tissue paper. Dry waxed tissue paper (used in florist shops where flowers are wet) works well too but doesn't get heavier in high humidity environments. Here's a video of a walkalong made from sliced foam sliced with a deli slicing machine:
New World's Slowest Walkalong Glider! Under 1 mph! (0 min 44 sec)


This particular design does not appear to have much ballast up front. It appears to make use of the increased updraft closer to the paddle to trim the nose down. When he stops moving the paddle the glider stops gliding.
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Old Aug 21, 2012, 11:48 PM
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Originally Posted by kcaldwel View Post
I think we must have picked it up from an article about the MacCready's in the '70s. Maybe their paper walk-along gliders were in an article about the Gossamer Albatross?

http://www.youtube.com/watch?v=7d80Mn8Rtik
The sciencetoymaker.org teacher now uses sliced foam. Here's his latest video progress report:
Walkalong Foam Glider Progress Report (10 min 0 sec)


Notice how much slower the foam walkalongs go relative to the phonebook paper origami hang gliders. It's all in reducing the mass per unit area.
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Old Aug 22, 2012, 12:26 AM
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Originally Posted by x-surfer View Post
I believe the paperang design would work just as well with a lighter material. Walkalong gliding depends on properly trimming the glider as mentioned in Ed's TED talk. The lightest paper I have used is tissue paper. Dry waxed tissue paper (used in florist shops where flowers are wet) works well too but doesn't get heavier in high humidity environments. Here's a video of a walkalong made from sliced foam sliced with a deli slicing machine:
http://www.youtube.com/watch?v=1-Yfoor5YM8&

This particular design does not appear to have much ballast up front. It appears to make use of the increased updraft closer to the paddle to trim the nose down. When he stops moving the paddle the glider stops gliding.
While that is really amazing, it just seems to take the elegance out of flight, especially with the oscillatory motion. I find much more beauty in an aircraft that can flight straight with a near-horizontal glide slope.
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Old Aug 22, 2012, 03:38 AM
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Originally Posted by DPATE View Post
While that is really amazing, it just seems to take the elegance out of flight, especially with the oscillatory motion. I find much more beauty in an aircraft that can flight straight with a near-horizontal glide slope.
The beauty of that video is only evident if you notice his shoes on the floor and realize how slow he is walking. The plane is flying with barely a wisp of lift. If you look at his comment then it's obvious that he deliberately trimmed it tail heavy (the reason for the porpoising) to get the lowest possible glide speed. And the fact that he achieved it is beautiful.

Jagwings don't need to be trimmed as such. They can easily be trimmed with a good deal of static margin resulting in a fairly flat glide slope. Search for them on youtube to see how others trim them.

The jagwing design per se is beautiful for another reason. It doesn't fly like airplanes or buzzards. Rather, it flies more like butterflies and hummingbirds (now don't tell me that hummingbird flight is not elegant). The jagged leading edge is a deliberate part of the design that is used to create vortices from which it gains a large portion of its lift. This makes perfect sense at these scales and Reynolds numbers. It's one of the few designs that I've seen to deliberately utilize vortex lift.
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Old Aug 23, 2012, 09:43 PM
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Originally Posted by x-surfer View Post
The trick is lighter material for slower flight. I still can't believe how easy it gets:
http://www.youtube.com/watch?v=bwFtzwtRh_M&feature=plcp

I'm pretty sure this is sliced foam with a ballast of some kind.
I think they trace the pattern onto paper then use the paper as a template over the sliced foam. If you look closely at 8 seconds into the video you can see two layers on the right wing. This technique is used by sciencetoymaker.org too. At 30 seconds into the video you see the template being applied to a sheet of thin sliced foam:
Part 4 Air Surfing Kit (9 min 12 sec)
:
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Old Aug 26, 2012, 01:19 AM
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Thank you guys. There's a whole load of stuff I've learnt in these posts.
Ed
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Old Aug 28, 2012, 12:25 PM
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Airworthiness

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Thank you guys. There's a whole load of stuff I've learnt in these posts.
Ed
I'd like to bring up the subject of airworthiness because Ed's talk is the foundation of making paper airplanes airworthy. Each real airplane needs to have an airworthiness certificate and to be inspected on a regular basis (either 100 hour or annual inspections, I think) because real planes get banged up too. For example a hard scrape to the wing can change the wing washout and cause a tip stall and incipient spin at low speed, for example.
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Old Aug 29, 2012, 03:18 AM
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I'd like to bring up the subject of airworthiness because Ed's talk is the foundation of making paper airplanes airworthy. Each real airplane needs to have an airworthiness certificate and to be inspected on a regular basis (either 100 hour or annual inspections, I think) because real planes get banged up too. For example a hard scrape to the wing can change the wing washout and cause a tip stall and incipient spin at low speed, for example.
What an interesting observation. I'd not thought about it, but it is true that I have spent a lot of time making planes that are stable and able to keep their structural integrity while in flight, even when thrown hard. It's different to dart shapes which bend when you hold them, expand when you let go, bend again while flying at different speeds. When I demonstrate the Paperang, I always have to ask the little kids to pick it up by the centre, otherwise they always grab a wingtip and bend it. They seem to have no concept that something I make to millimetre accuracy might work differently if they put a centimetre bend in it!

By the way I've now been in touch with Slater Harrison as a direct result of these conversations, and discovering how my area of investigations over the years have paralleled the walkalong glider developments. For example, I use the flying wing shape because of my hang gliding background, and because I think a really accurate fuselage and tail is too much to expect from paper or other quick-building materials. Walkalong folk use flying wings because they are noticeably less sensitive to pitch perturbations when the 'slope' is brought closer or further away from the glider. I guess there have been maybe 20 or so (Slater's estimate) pioneers working on this sort of thing over the last 30 or so years. Each is discovering post-internet that others have been in the same field. I think we all thought we were at the leading edge, but it turns out there have been so many different leading edges!
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Old Sep 01, 2012, 01:18 AM
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Originally Posted by Edmond Hui View Post
What an interesting observation. I'd not thought about it, but it is true that I have spent a lot of time making planes that are stable and able to keep their structural integrity while in flight, even when thrown hard.

By the way I've now been in touch with Slater Harrison as a direct result of these conversations, and discovering how my area of investigations over the years have paralleled the walkalong glider developments. For example, I use the flying wing shape because of my hang gliding background, and because I think a really accurate fuselage and tail is too much to expect from paper or other quick-building materials. Walkalong folk use flying wings because they are noticeably less sensitive to pitch perturbations when the 'slope' is brought closer or further away from the glider. I guess there have been maybe 20 or so (Slater's estimate) pioneers working on this sort of thing over the last 30 or so years. Each is discovering post-internet that others have been in the same field. I think we all thought we were at the leading edge, but it turns out there have been so many different leading edges!
I guess walkalong gliding is something to do with an airworthy paper airplane. Have you seen the TED talk by Paul Macready which ends with a walkalong glider flight by his son Tyler? Here it is:
http://www.ted.com/talks/lang/en/pau...lar_wings.html
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Old Sep 01, 2012, 02:19 PM
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Originally Posted by Edmond Hui View Post
What an interesting observation. I'd not thought about it, but it is true that I have spent a lot of time making planes that are stable and able to keep their structural integrity while in flight, even when thrown hard. It's different to dart shapes which bend when you hold them, expand when you let go, bend again while flying at different speeds. When I demonstrate the Paperang, I always have to ask the little kids to pick it up by the centre, otherwise they always grab a wingtip and bend it. They seem to have no concept that something I make to millimetre accuracy might work differently if they put a centimetre bend in it!
The technical details of an airplane's airworthiness or type-certificate include a raft of airspeeds (v speeds) which define the flight envelope of a given aircraft. There's the maneuvering speed for turbulent air and the never exceed speed above which the plane starts bending and may suffer structural damage. For a walkalong glider type model, there is a flight envelope which is about at walking speed.
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Old Sep 01, 2012, 02:34 PM
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Originally Posted by Edmond Hui View Post
I guess there have been maybe 20 or so (Slater's estimate) pioneers working on this sort of thing over the last 30 or so years. Each is discovering post-internet that others have been in the same field. I think we all thought we were at the leading edge, but it turns out there have been so many different leading edges!
I was a glider pilot and flying in turbulent air was hard for me because I didn't fly often enough to get over my airsickness. Also trying to find lift was always a challenge. Walkalong gliding makes soaring easier for me in that I have control of the lift. I think it's about time the lift followed the plane around!!!
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Old Sep 01, 2012, 02:46 PM
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Originally Posted by Edmond Hui View Post
Walkalong folk use flying wings because they are noticeably less sensitive to pitch perturbations when the 'slope' is brought closer or further away from the glider.
The ridge lift generated by the paddle is stronger the closer to the paddle the glider gets. This gradient produces a nose down tendency to the glider. If a walkalong glider is trim slightly nose up there is a nice pitch stability in that if the glider gets too close to the paddle it speeds up and if it gets too far away the nose pitches up and it slows down.
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Old Sep 01, 2012, 05:16 PM
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The ridge lift generated by the paddle is stronger the closer to the paddle the glider gets. This gradient produces a nose down tendency to the glider. If a walkalong glider is trim slightly nose up there is a nice pitch stability in that if the glider gets too close to the paddle it speeds up and if it gets too far away the nose pitches up and it slows down.
Yes to all that- I was a hang glider pilot and of course I was exploring the air very close to the slope- I mean raising a wingtip to avoid bushes. There were some magical days and magical conditions when you could fly so slow and so close it didn't matter if you crashed.

I've just today received some foam sheets from Slater and will be experimenting with those. I did see Tyler's TED talk when it was first put on the TED site. It was the first time I'd seen walkalong gliding.
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Old Sep 02, 2012, 05:52 AM
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Paperang inviscid L/D: about 50

Dart inviscid L/D: about 15

The dart geometry does have some advantages at hypersonic speeds...
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Old Sep 02, 2012, 10:05 AM
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Paperang inviscid L/D: about 50

Dart inviscid L/D: about 15

The dart geometry does have some advantages at hypersonic speeds...
I'll give you that. Or even at transonic speeds.
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